In February, Lithuanian prosecutors reopened an investigation into whether the CIA ran one of its notorious "black sites" on the outskirts of Vilnius in the early 2000s.

Evidence has been growing since 2009 that, alongside its secret prisons in Poland, Romania, Thailand, Afghanistan and Morocco, the CIA also ran a Lithuanian site in 2004-05 where they may have tortured "high-value" terror suspects including Mustafa al-Hawsawi and Abu Zubaydah. Both men are currently being held at Guantanamo.

Photograph: Mindaugas Kulbis/AP via The Guardian

The prison likely closed in 2005 or 2006, after news about potential secret CIA prisons in Macedonia, Poland and Romania were reported in the press. Cargo planes with markings associated with Richmor Aviation, an airline now known to have conducted CIA rendition flights, were seen coming and going from Vilnius. Other reports say that when the facility was being renovated, local people who stopped by looking for work were turned away by English-speaking guards. In 2009, when the story about the Vilnius black site was first reported, Lithuanian president Dalia Grybauskaitė was quoted as saying, "If this is true, Lithuania has to clean up, accept responsibility, apologize, and promise that it will never happen again." If proven, this would make Lithuania one of only four European countries to permit the Americans to commit torture on their territory.

At first the prosecutors refused to reopen the case. Less than a month later, in February of this year, they changed their minds. The investigation will focus on whether Al-Hawsawi was in fact held in Vilnius.